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CASE REPORTDOI: 10.1590/1516-3180.2016.0253040117

Leiomyoma of the breast parenchyma: a case report and review of the literatureRodrigo Gregório BrandãoI, Simone EliasII, Afonso Celso Pinto NazárioIII, Maria do Carmo Guedes Alcoforado AssunçãoIV,

Camilla Cirone Esposito PapaV, Gil FacinaVI

Discipline of Mastology, Department of Gynecology, Universidade Federal de São Paulo (UNIFESP), São Paulo (SP), Brazil

ABSTRACTINTRODUCTION: Benign tumors are often seen in breast screening examinations. However, the differen-tial diagnosis is not always simple because of radiological similarity between the different benign lesions. CASE REPORT: We present a rare case report of leiomyoma of the breast parenchyma in a 68-year-old asymptomatic patient. The mammographic and ultrasonographic findings were similar to those observed in benign lesions. CONCLUSION: The histopathological diagnosis requires careful differentiation from lesions that have smooth muscle proliferation, especially leiomyosarcoma. The most commonly performed treatment is re-section of the lesion with free margins. Although breast leiomyoma is rare, it should be considered among the differential diagnoses for breast nodules of benign appearance. Resection with safety margins proved to be the only treatment needed.

IMedical Doctor and Doctoral Student, Discipline of Mastology, Department of Gynecology, Universidade Federal de São Paulo (UNIFESP), São Paulo (SP), Brazil.IIMedical Doctor, Doctorate in Medicine and Assistant Professor, Discipline of Mastology, Department of Gynecology, Universidade Federal de São Paulo (UNIFESP), São Paulo (SP), Brazil.IIIMedical Doctor, Doctorate in Medicine and Full Professor of the Department of Gynecology, Universidade Federal de São Paulo (UNIFESP), São Paulo (SP), Brazil.IVMedical Doctor, Doctorate in Medicine and Head of the Locus Laboratory, Department of Pathology, Universidade de São Paulo (USP), São Paulo (SP), Brazil.VUndergraduate Student, Faculdade Santa Marcelina (FASM), São Paulo (SP), Brazil.VIMedical Doctor, Doctorate in Medicine, Full Professor and Head of the Discipline of Mastology, Department of Gynecology, Universidade Federal de São Paulo (UNIFESP), São Paulo (SP), Brazil.

KEY WORDS:Breast. Ultrasonography.Leiomyoma. Breast neoplasms.Diagnosis.

INTRODUCTIONLeiomyoma is considered to be the rarest non-epithelial tumor of the breast.1 It occurs more fre-quently in the retroareolar region because of the greater amount of smooth muscle in this location.2 Its presence in the mammary parenchyma is extremely rare, with fewer than 30 cases reported so far in the literature.3 The clinical, radiological and pathological characteristics do not differ mark-edly from those observed in the most frequent benign lesions. We report a case of leiomyoma in the breast parenchyma that was seen in our service and conducted a review of the literature, with special attention to radiological features that have been described so far.

CASE REPORTA 68-year-old woman was seen at the Division of Mastology, Department of Gynecology of the Federal University of São Paulo (Universidade Federal de São Paulo, UNIFESP) with a non-palpable tumor that had been detected through screening mammography. The patient presented controlled hypertension and minor degenerative osteoarticular alterations. She reported having had three preg-nancies and two deliveries, with thirty months of breastfeeding. She said that she did not have any other symptoms such as papillary flow or cutaneous lesions. She reported having had routine annual mammograms and that she had not had any previous surgery or biopsies. The mammogram per-formed two years earlier did not show any abnormalities. The physical examination was unremark-able, with no evidence of any palpable mass, skin changes or axillary lymphadenopathy.

Imaging findings Mammographic images showed an isodense circumscribed oval mass measuring 1.8 x 1.0 cm that was located at the junction of the upper quadrants of the left breast. Sonographic images of the left breast showed a hypoechoic homogenous oval mass measuring 1.4 x 0.7  cm that

CASE REPORT | Brandão RG, Elias S, Nazário ACP, Assunção MCGA, Papa CCE, Facina G

178 Sao Paulo Med J. 2018;136(2):177-81

was horizontal and parallel to the skin. It had two lobulations and circumscribed margins, and was coincident with the location described through mammography (Figure 1). The lesion did not present any posterior acoustic shadow, hyperechoic halo or other associated abnormal features. The mass was classified as being in Breast Imaging-Reporting and Data System (BI-RADS) cat-egory 4.

Histopathological findings An ultrasound-guided breast core biopsy with a 12-gauge needle was performed and five fragments were obtained. The

Figure 1. Sonographic findings in breast leiomyoma, demonstrating a hypoechoic oval mass that was predominantly circumscribed but sometimes showed microlobulated margins, and which was parallel to the breast skin. It was classified via ultrasonography in Breast Imaging-Reporting and Data System (BI-RADS) category 4.

A B

Figure 2. Histological sections revealing circumscribed appearance of the lesion, with proliferation of fusiform pattern and lack of atypical forms. Staining with hematoxylin and eosin (10 x and 40 x).

pathological evaluation showed a mesenchymal neoplasm with muscle differentiation. The patient underwent surgical excision of the lesion. The histological findings revealed a circumscribed lesion with a pattern of fusiform proliferation and formation of interlaced bundles and fascicles (Figure 2). No cellular atypia, necrosis or mitotic figures was found. Immunohistochemical stains for CD34 and S100 were positive, and negative for des-min and smooth muscle actin. A diagnosis of smooth muscle tumor, and specifically mammary parenchyma leiomyoma, was established. There was no recurrence of the lesion after follow-up of 60 months.

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DISCUSSIONEven though Strong’s first paper on breast leiomyoma was pub-lished in 1913, knowledge of the etiology of this condition remains uncertain.4 It has been taken to originate from smooth-muscle angiomatous cells, given the “angiocentric” prolifera-tion of smooth muscle that is observed. This theory is rein-forced through the observation that blood vessels are present at locations showing defects or artefacts of histological fixation.5 Current immunohistochemical findings rule out teratogenic ori-gins. Uncertainty remains regarding theories of embryological displacement of smooth muscle cells of the areola, and regard-ing an origin from multipotent mesenchymal cells. These were proposed in the first half of the twentieth century by Melnick6 and Shauder.7

Breast leiomyoma occurs predominantly in women, with only one case reported in a man.2 The age of highest incidence is between 40 and 60 years. It presents as an isolated tumor of slow growth, with similar characteristics to the most common benign tumors.8-10 The presence of pain was observed in only three cases, being more frequent in tumors of areolar location due to the contraction of neoplastic muscle cells.11

Physical examination usually reveals a mobile nodule with well-defined limits and fibroelastic consistency, although sometimes it has been reported to have hardened consistency.12-14 Mammographic images have been described as showing an isodense or hyper-dense oval mass, with outlines that are most often circumscribed (Table 1).1,13,15-21 Microcalcifications relating to leiomyoma have never been described.15,16,22,23

The effectiveness of mammography is limited in relation to lesions measuring less than 1.0 cm and breasts with predominant glands. Sonography frequently shows a hypoechoic mass with well-defined limits and oval shape.17 Presence of lobulations has frequently been observed. Growth parallel to the skin has been observed in 100% of the cases. No well-defined posterior acous-tic shadowing has been described.18

Magnetic resonance imaging findings were first reported by Minami et al. They described a circumscribed oval nodule, with hypersignal in T1 and T2, and homogeneous enhance-ment after gadolinium infusion. They pointed out that pres-ence of degeneration can influence the signal pattern in dif-ferent sequences, as noted in leiomyoma in other regions of the body.16

The differential diagnosis should be done in relation to lesions that have smooth muscle proliferation in the absence of epithelial or ductal structures. In this context, the lesions that comprise the differential diagnosis are angioleiomyoma, fibro-adenoma and malignant phyllodes tumor.24-26 Because mature adipose tissue is needed to identify cases of hamartoma, this lesion does not provide difficulties in the differential diagnosis.5

Author Year Radiological findings

Lauwers et al.20

1990MMG: Well-defined focal asymmetry; benign appearance without calcifications or loss of contoursUS: None

Nazário et al.13

1995MMG: Hyperdense, homogeneous image with defined regular margins.US: None

Kaufman and Hirsch1

1996MMG: Dense breast without identifiable abnormalities.US: None

Son et al.18 1998MMG: Oval nodule with well-defined marginsUS: Isoechoic oval nodule; slightly lobulated with well-defined margins

Sidoni et al.17

1999MMG: Bulky oval mass, with circumscribed margins.US: Hypoechoic oval mass, with well-defined margins.

Pourbagher et al.15

2005

MMG: Nodule with well-defined margins without calcifications.US: Circumscribed hypoechoic solid oval mass, with well-defined margins.

Ende et al.19 2007MMG: Isodense oval nodule with indistinct margins.US: Not viewed.

Minami et al.16

2011MMG: Hyperdense oval nodule with indistinct margins, without spicules or microcalcifications.US: Hypoechoic nodule, with well-defined margins.

Shah et al.30 2013MMG: Circumscribed isodense oval nodule.US: None

Brandão et al. (present case)

2015MMG: Circumscribed isodense oval nodule.US: Circumscribed hypoechoic oval nodule with rare lobulations.

Table 1. Radiological findings from 10 cases of mammary leiomyoma.

MMG = mammogram. US = ultrasonography

In cases of lesions suggestive of leiomyoma, leiomyosarcoma is the main situation that needs to be ruled out.19,27

Presence of 2-16 mitotic figures per 10 high-power figures is the main feature for diagnosing leiomyosarcoma. According to Pourbagher, presence of 1-3 mitotic figures might be considered to represent an intermediate category because of the higher risk of local recurrence and, therefore, treatment that is more radical.15 Boscaino et al. reported local recurrence in two cases initially diag-nosed as leiomyoma. Histological reevaluation of the lesions found presence of increased mitotic activity, and the lesions were reclas-sified as smooth-muscle neoplasms of undetermined prognosis.28 In patients with a confirmed diagnosis of breast leiomyoma, no cases of local recurrence have been reported to date.11-19,22-27

We reviewed the literature in MEDLINE and Lilacs using the English keywords “leiomyoma”, “fibroid tumors”, “benign tumor”, “benign neoplasms”, “breast tumor”, “breast neoplasms” and “ultra-sonography”. We found 30 case reports that described patients with leiomyoma in the breast parenchyma (Table 2).

In reviewing treatments that have been implemented, a wide range of interventions can be identified, from lumpectomy to radi-cal mastectomy (Table 3).1,2,4-10,13,15-21,24,29 However, since the report by Lauwers in 1990, the standard treatment has been resection with free margins.20,21

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180 Sao Paulo Med J. 2018;136(2):177-81

F = female; M = male; W = white; B = black; A = Asian; R = right; L = left; UOQ = upper outer quadrant; UIQ = upper inner quadrant; JIQ = junction of inner quadrants; JOQ = junction of outer quadrants; JUQ = junction of upper quadrants; JLI = junction of lower quadrants; LOQ = lower outer quadrant.

Table 3. Clinical findings from 20 cases of breast leiomyomaAuthor Year Sex Race Age (years) Symptoms Location Size (cm) TherapyStrong4 1913 F W 46 Discomfort UOQ R 6.0 -Schauder7 1927 F W 34 Discomfort UOQ R 3.0 NodulectomyMelnick6 1932 F W 45 Pain JLI R “small” Total mastectomyLeibowich and Lenz8 1940 F W 58 Discomfort Midline 13.8 Total mastectomyStein9 1943 F W 54 Discomfort UIQ R 4.0 Radical mastectomyCraig10 1947 F B 40 Pain LOQ L 10 NodulectomyLibcke247 1969 F W 50 Hardening JUQ R 0.5 NodulectomyHaagensen29 1971 F - 52 None Midline 2.5 NodulectomyDiaz-Arias et al.5 1989 F W 69 None UOQ R 2.0 NodulectomyLauwers et al.20 1990 F B 43 Mammographic finding JUQ L 0.5 Resection with free marginsNazario et al.13 1995 F B 53 Nodule UIQ L 10 Resection with free marginsKaufman and Hirsch1 1996 F W 48 Nodule Midline R 1.0 Resection with free marginsSon et al.18 1998 F A 50 Pain UOQ R 1.0 Resection with free marginsSidoni et al.17 1999 F - 48 Nodule UOQ L 4.0 Resection with free marginsPourbagher et al. 15 2005 F - 47 Mammographic finding JIQ L 2.5 Resection with free marginsEnde et al.19 2007 F - 48 Mammographic finding JIQ L 1.2 Resection with free marginsMinami et al.16 2011 F A 63 Mammographic finding UIQ R 1.6 Excisional biopsyShah et al.21 2013 F W 27 Nodule UIQ L 2.0 Excisional biopsyStrader et al.2 2013 M W 70 Nodule JOQ L 7.0 Resection with free marginsBrandão et al. (current case) 2015 F W 68 Mammographic finding JUQ L 1.4 Resection with free margins

Table 2. Search of the literature in medical databases for case reports on leiomyoma in the breast parenchyma. The search was conducted on December 5, 2016

Database Search strategies URL Papers found Related papers

MEDLINE (via PubMed)

((“leiomyoma”[MeSH Terms] OR “leiomyoma”[All Fields]) OR “fibroid tumors”[All Fields] OR (“leiomyoma”[MeSH Terms]

OR “leiomyoma”[All Fields] OR “fibromyoma”[All Fields]) OR “benign tumor”[All Fields] OR “benign neoplasms”[All

Fields] OR “benign tumor”[All Fields]) AND (“breast/pathology”[Mesh Terms] OR “breast neoplasms”[MeSH Terms] OR “breast cancer”[All Fields] OR “breast tumor”[All Fields] OR “mammary cancer”[All Fields] OR “cancer of breast”[All Fields])

AND (“ultrasonography”[MeSH Terms] AND (“diagnostic imaging”[Subheading] OR (“diagnostic”[All Fields] AND

“imaging”[All Fields]) OR “diagnostic imaging”[All Fields] OR “ultrasonography”[All Fields] OR “ultrasonography”[MeSH Terms])

OR (“diagnostic imaging”[Subheading] OR (“diagnostic”[All Fields] AND “imaging”[All Fields]) OR “diagnostic imaging”[All

Fields] OR “ultrasound”[All Fields] OR “ultrasonography”[MeSH Terms] OR “ultrasonography”[All Fields] OR “ultrasound”[All

Fields] OR “ultrasonics”[MeSH Terms] OR “ultrasonics”[All Fields]) OR (“ultrasonography, mammary”[MeSH Terms] OR

(“ultrasonography”[All Fields] AND “mammary”[All Fields]) OR “mammary ultrasonography”[All Fields] OR (“mammary”[All

Fields] AND “ultrasonography”[All Fields])))

http://bit.ly/2mCc4uj 117 24

LILACS (via Bireme)

mh: leiomyoma OR tw:leiomyoma OR tw:“fibroid tumors” OR tw:fibromyoma OR tw:“benign tumor” OR tw:“benign neoplasms” OR tw:“benign tumor”)) AND (tw:((“breast/pa” OR mh:c04.588.180

OR mh:c17.800.090.500 OR mh:“breast neoplasms” OR tw:“breast cancer” OR tw:“mammary cancer” OR tw:“breast neoplasms”))) AND (tw:ultrasound OR tw:ultrasonography))

AND (instance:“regional”) AND (db:(“LILACS”))) AND (instance:“regional”) AND ( mj:(“Mama”))

https://goo.gl/HbOEvW

42 6

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Sao Paulo Med J. 2018;136(2):177-81 181

CONCLUSIONIn conclusion, it can be said that leiomyoma in mammary tissue is an extremely rare condition. The clinical presentation does not differ from that observed in the most common benign tumors of the breast. The radiological findings are characteristically benign, which helps rule out the hypothesis of cancer. In histopathologi-cal evaluations, it is important to pay attention to the differential diagnosis of leiomyosarcoma. The standard recommended treat-ment is local resection with free margins. In this situation, the risk of local recurrence is practically zero.

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Sources of funding: None

Conflict of interest: None

Date of first submission: November 26, 2016

Last received: December 30, 2016

Accepted: January 4, 2017

Address for correspondence:

Rodrigo Gregório Brandão

Departamento de Ginecologia, Disciplina de Mastologia, Universidade

Federal de São Paulo (UNIFESP)

Rua Napoleão de Barros, 608

São Paulo (SP) - Brazil

CEP: 040002-233

Tel: (+55 11) 5576-4848 (Ramal 2856)

Cel. (+ 55 11) 98161-7511

Fax: (+55 11) 4521-2604

E-mail: rodrigobrandao.masto@gmail.com

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